[ci] [R-package] clang16 CI jobs failing: "error: templates must have C++ linkage"

[jameslamb]

Description

(clang16, R-devel) CI jobs have been failing here for the last few days, with this error in the installation of {fs}

In file included from error.cc:1:
In file included from ./error.h:5:
In file included from /opt/R/devel/lib/R/include/Rinternals.h:47:
In file included from /opt/R/devel/lib/R/include/R_ext/Error.h:30:
In file included from /opt/R/devel/lib/R/include/R_ext/RS.h:30:
/usr/lib/llvm-16/bin/../include/c++/v1/cstring:117:1: error: templates must have C++ linkage
template <class _Tp>
^~~~~~~~~~~~~~~~~~~~
/opt/R/devel/lib/R/include/Rinternals.h:37:1: note: extern "C" language linkage specification begins here
extern "C" {
^
1 error generated.
make[1]: *** [/opt/R/devel/lib/R/etc/Makeconf:202: error.o] Error 1
make[1]: Leaving directory '/tmp/RtmpZZyG7J/R.INSTALLb894784240/fs/src'
ERROR: compilation failed for package ‘fs’

That looks like an incompatibility between R's own headers and clang-16, not something LightGBM needs to fix.

Reproducible example

This is happening in all CI builds.

Example from #6600: (build link)

Environment info

N/A

Additional Comments

{fs} is passing this check currently on CRAN: https://cran.r-project.org/web/checks/check_results_fs.html

CRAN is still running the clang16 check: https://cran.r-project.org/web/checks/check_issue_kinds.html